[ARM] pxa: embed body of pxa320_init_mfp()

pxa320_init_mfp() is simple enough to be embedded into pxa320_init()
to simplify the code a bit.

Signed-off-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>